Widely used classes, such as those in java.io and java.util, are well known to the typical Java programmer.
When importing such classes, it's reasonable to use an abbreviated style:

import java.io.*;import java.util.*;

When importing classes that are not among the most widely used, one should probably
use another style, in which each class has an explicit import statement.
If a class is unfamiliar to a reader, an explicit import makes it easier to find related documentation.

Example

For example, if a class imports items from the Apache Commons FileUpload tool, then instead of :